Such an assembly is described in document EP-A-1 232 932, for example.
The structure described in that document enables the visible outlines of the light units to be positioned automatically and permanently relative to the ends of the corresponding fenders and to the bumper skin. Simultaneously, that structure ensures accurate relative positioning of the ends of the fenders and of the bumper skin.
In order to improve the appearance of the vehicle, it can also be desirable to ensure continuity of appearance for the light units and the bumper skin with other bodywork elements, such as the hood of the vehicle.